Shift register unit, gate drive circuit and method of driving the same

ABSTRACT

A shift register unit cascaded in a gate drive circuit, wherein the shift register unit comprises: a control circuit configured to output a control signal, at least two buffer circuits coupled to the control circuit, each of the at least two buffer circuits configured to output scan signal to a gate line. As such, the scan signals output from the at least two buffer circuits would be synchronized so that the gate lines respectively coupled to the two buffer circuits can be scanned simultaneously.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application under 35 U.S.C. § 371of International Application No. PCT/CN2017/108587, filed Oct. 31, 2017,which claims priority of the Chinese Patent Application No.201710054473.3, entitled “GATE DRIVE CIRCUITS AND METHODS OF DRIVING THESAME AND ASSOCIATED DISPLAY DEVICES” filed on Jan. 22, 2017, thedisclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates in general to a display technology, andmore particularly relates to shifter register unit, gate drive circuit,method of driving the same.

BACKGROUND

A display device such as a liquid crystal display (LCD) may include anarray substrate and a color film substrate that are paired together. Thearray substrate may include a number of gate lines and a number of datalines crossing each other at right angles. Each gate line may cross adata line and thus define a subpixel. Therefore, the number and spacingof the gate lines and data lines determine the intrinsic resolution ofthe display device.

SUMMARY

Embodiments disclosed herein provide shift register unit, gate drivecircuit, methods of driving the gate drive circuit, which can enableswitching between a plurality of sets of pixel resolutions.

According to one aspect, there is provided a shift register unitcascaded in a gate drive circuit, wherein the shift register unitcomprises: a control circuit configured to output a control signal, atleast two buffer circuits coupled to the control circuit, one of the atleast two buffer circuits configured to output scan signal to a gateline, optionally, the scan signal may be gate scan signal, wherein thecontrol circuit comprises a first pull-up control sub-circuit coupled toa first signal input terminal, a signal output terminal of the controlcircuit, and a first voltage terminal, the first pull-up controlsub-circuit configured to output a signal of the first voltage terminalto the signal output terminal of the control circuit under control of asignal of the first signal input terminal; a first pull-down controlsub-circuit coupled to a first clock signal terminal, a second clocksignal terminal, the first signal input terminal, a second voltageterminal, a fourth voltage terminal, and a first pull-down node, thefirst pull-down control sub-circuit configured to control a voltagelevel of the first pull-down node under control of signals of the firstclock signal terminal, the second clock signal terminal and the firstsignal input terminal; a second pull-down control sub-circuit coupled tothe first clock signal terminal, the second clock signal terminal, thefirst signal input terminal, a third voltage terminal, the fourthvoltage terminal, and a second pull-down node, the second pull-downcontrol sub-circuit configured to control a voltage level of the secondpull-down node under control of signals of the first clock signalterminal, the second clock signal terminal and the first signal inputterminal; a first pull-down sub-circuit coupled to the first pull-downnode, the signal output terminal of the control circuit, and the fourthvoltage terminal, the first pull-down sub-circuit configured to pull avoltage at the signal output terminal of the control circuit down to thevoltage of the fourth voltage terminal under control of a voltage levelof the first pull-down node; a second pull-down sub-circuit coupled tothe second pull-down node, the signal output terminal of the controlcircuit, and the fourth voltage terminal, the second pull-downsub-circuit configured to pull the voltage of the signal output terminalof the control circuit down to the voltage of the fourth voltageterminal under control of a voltage level of the second pull-down node;and a reset sub-circuit coupled to a second signal input terminal, thefirst voltage terminal, and the second pull-down node, the reset modulebeing configured to output a voltage of the first voltage terminal tothe second pull-down node under control of a signal of the second signalinput terminal; each of the at least two buffer circuits comprises asecond pull-up control sub-circuit coupled to a pull-up control node,the second voltage terminal, the third voltage terminal, and the signaloutput terminal of the control circuit, the second pull-up controlsub-circuit configured to turn on and output a signal of the signaloutput terminal of the control circuit to the pull-up control node undercontrol of a signal of the second voltage terminal and a signal of thethird voltage terminal; a pull-up sub-circuit coupled to the pull-upcontrol node, a third clock signal terminal, and a signal outputterminal of the buffer circuit, the pull-up module being configured tooutput a signal of the third clock signal terminal to the signal outputterminal of the buffer circuit under control of a voltage of the pull-upcontrol node; a third pull-down sub-circuit coupled to the firstpull-down node, the fourth voltage terminal, and the signal outputterminal of the buffer circuit, the third pull-down module beingconfigured to pull a voltage of the signal output terminal of the buffercircuit down to the voltage of the fourth voltage terminal under controlof a the first pull-down node; and a fourth pull-down sub-circuit iscoupled to the second pull-down node, the fourth voltage terminal, andthe signal output terminal of the buffer circuit, the fourth pull-downsub-circuit configured to pull the voltage of the signal output terminalof the buffer circuit down to the voltage of the fourth voltage terminalunder control of a voltage level of the second pull-down node.

According to another aspect of the disclosure, there is provided a gatedrive circuit, comprising: Q groups of shift register units cascaded inseries, one of the Q groups of shift register units cascaded in seriescomprising S shift register units cascaded in series, each of the Sshift register units for outputting scan signals to M gate lines, andS×M clock signal lines, M clock signal lines of which is coupled to oneof the S shift register units in each of the Q groups of shift registerunits, Q, S and M are integer, S≥2, M≥2; wherein each of the S shiftregister units comprises a control circuit configured to output acontrol signal, M buffer circuits coupled to the control circuit, andS×M buffer circuits coupled to the S×M clock signal lines forsequentially providing S×M clock signals respectively in one group ofthe Q groups of shift register units cascaded in series, wherein each ofthe M buffer circuits is configured to be controlled by the controlsignal and one of the M clock signals provided by the M clock signallines to output a scan signal to a gate line of the M gate lines.

According to still another aspect of the disclosure, there is provided amethod for driving a gate drive circuit, the gate drive circuitcomprises Q groups of shift register units cascaded in series, one ofthe Q groups of shift register units cascaded in series comprising Sshift register units cascaded in series, each of the S shift registerunits comprises a control circuit configured to output a control signal,M buffer circuits coupled to the control circuit, each of the S shiftregister units for outputting scan signals to M gate lines, and S×Mclock signal lines, M clock signal lines of which is coupled to one ofthe S shift register units, Q, S and M are integer, S≥2, M≥2; the methodcomprising: providing S×M clock signals time-sequentially from a 1stclock signal to a S×M-th clock signal through the S×M clock signal linesrespectively to the S shift register units in each of the Q groups ofshift register units; wherein providing M clock signals through the Mclock signal lines to the M buffer circuits in each of the S shiftregister units.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

To better illustrate the embodiments of the disclosure or the prior artsolutions, a brief description of the accompanying drawings for use withthe illustration of the embodiments or the prior art is provided below.It is obvious that the drawings described below depict merely someembodiments of the disclosure and those of ordinary skill in the art canobtain other drawings based on the arrangements shown in these drawingswithout making inventive efforts.

FIG. 1 shows a schematic diagram of a gate drive circuit according to anembodiment of the disclosure.

FIG. 2 shows a schematic diagram illustrating an example of a gate drivecircuit of FIG. 1 in which each shift register unit includes four buffercircuits.

FIG. 3 shows a timing diagram of the control signal used by the gatedrive circuit of FIG. 2 when the intrinsic resolution is displayed.

FIG. 4 shows a timing diagram of the control signal used by the gatedrive circuit of FIG. 2 when a half of the intrinsic resolution isdisplayed.

FIG. 5 shows a timing diagram of the control signal of used by gatedrive circuit of FIG. 2 when a quarter of the intrinsic resolution isdisplayed.

FIG. 6 shows a schematic diagram illustrating an example of a gate drivecircuit of FIG. 1 in which each shift register unit includes two buffercircuits.

FIG. 7 shows a timing diagram of the control signal used by the gatedrive circuit of FIG. 6 when the intrinsic resolution is displayed.

FIG. 8 shows a timing diagram of the control signal used by the gatedrive circuit of FIG. 6 when a half of the intrinsic resolution isdisplayed.

FIG. 9 shows a schematic diagram illustrating any one of the controlcircuits in the gate drive circuit as illustrated in FIG. 2 or FIG. 6.

FIG. 10 shows a schematic diagram illustrating any of the buffercircuits in the gate drive circuit as illustrated in FIG. 2 or FIG. 6.

FIG. 11 is a schematic diagram illustrating a circuit formed byconnecting the control circuit as shown in FIG. 9 with the buffercircuit as shown in FIG. 10.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Hereinafter embodiments of the disclosure will be described in suchdefinite and comprehensive detail with reference made to theaccompanying drawings. It is obvious that the embodiments describedherein constitute merely part rather than all of the embodiments of thedisclosure. Therefore, all other embodiments obtained by those ofordinary skill in the art in light of the embodiments disclosed hereinwithout making inventive efforts shall all fall in the scope of thedisclosure.

As the high-definition technology continues to develop, the intrinsicresolution of the display devices have become increasingly higher inorder to meet the display requirements for high-definition images.However, when the resolution of the image to be displayed is lower thanthe intrinsic resolution of the display device, unnecessary displaypower consumption may be caused if the display still shows the image atits intrinsic resolution.

In one embodiment, there is provided a shift register unit cascaded in agate drive circuit, wherein the shift register unit comprises: a controlcircuit configured to output a control signal, at least two buffercircuits coupled to the control circuit, each of the at least two buffercircuits configured to output scan signal to a gate line, wherein thecontrol circuit comprises a first pull-up control sub-circuit coupled toa first signal input terminal, a signal output terminal of the controlcircuit, and a first voltage terminal, the first pull-up controlsub-circuit configured to output a signal of the first voltage terminalto the signal output terminal of the control circuit under control of asignal of the first signal input terminal, a first pull-down controlsub-circuit coupled to a first clock signal terminal, a second clocksignal terminal, the first signal input terminal, a second voltageterminal, a fourth voltage terminal, and a first pull-down node, thefirst pull-down control sub-circuit configured to control a voltagelevel of the first pull-down node under control of signals of the firstclock signal terminal, the second clock signal terminal and the firstsignal input terminal; a second pull-down control sub-circuit coupled tothe first clock signal terminal, the second clock signal terminal, thefirst signal input terminal, a third voltage terminal, the fourthvoltage terminal, and a second pull-down node, the second pull-downcontrol sub-circuit configured to control a voltage level of the secondpull-down node under control of signals of the first clock signalterminal, the second clock signal terminal and the first signal inputterminal; a first pull-down sub-circuit coupled to the first pull-downnode, the signal output terminal of the control circuit, and the fourthvoltage terminal, the first pull-down sub-circuit configured to pull avoltage at the signal output terminal of the control circuit down to thevoltage of the fourth voltage terminal under control of a voltage levelof the first pull-down node; a second pull-down sub-circuit coupled tothe second pull-down node, the signal output terminal of the controlcircuit, and the fourth voltage terminal the second pull-downsub-circuit configured to pull the voltage of the signal output terminalof the control circuit down to the voltage of the fourth voltageterminal under control of a voltage level of the second pull-down node;and a reset sub-circuit coupled to a second signal input terminal, thefirst voltage terminal, and the second pull-down node, the reset modulebeing configured to output a voltage of the first voltage terminal tothe second pull-down node under control of a signal of the second signalinput terminal, each of the at least two buffer circuits comprises asecond pull-up control sub-circuit coupled to a pull-up control node,the second voltage terminal, the third voltage terminal, and the signaloutput terminal of the control circuit, the second pull-up controlsub-circuit configured to turn on and output a signal of the signaloutput terminal of the control circuit to the pull-up control node undercontrol of a signal of the second voltage terminal and a signal of thethird voltage terminal; a pull-up sub-circuit coupled to the pull-upcontrol node, a third clock signal terminal, and a signal outputterminal of the buffer circuit, the pull-up module being configured tooutput a signal of the third clock signal terminal to the signal outputterminal of the buffer circuit under control of a voltage of the pull-upcontrol node; a third pull-down sub-circuit coupled to the firstpull-down node, the fourth voltage terminal, and the signal outputterminal of the buffer circuit, the third pull-down module beingconfigured to pull a voltage of the signal output terminal of the buffercircuit down to the voltage of the fourth voltage terminal under controlof a the first pull-down node; and a fourth pull-down sub-circuit iscoupled to the second pull-down node, the fourth voltage terminal, andthe signal output terminal of the buffer circuit, the fourth pull-downsub-circuit configured to pull the voltage of the signal output terminalof the buffer circuit down to the voltage of the fourth voltage terminalunder control of a voltage level of the second pull-down node.

Optionally, the first pull-up control sub-circuit comprises: a firsttransistor, wherein a gate of the first transistor is coupled to thefirst signal input terminal, a first electrode of the first transistoris coupled to the first voltage terminal, and a second electrode thereofis coupled to the signal output terminal of the control circuit.

Optionally, the first pull-down control sub-circuit comprises: a secondtransistor, a third transistor, and a fourth transistor: wherein a gateof the second transistor is coupled to the first clock signal terminal,a first electrode of the second transistor is coupled to the secondvoltage terminal, and a second electrode thereof is coupled to a firstelectrode of the third transistor; wherein a gate of the thirdtransistor is coupled to the second clock signal terminal, and a secondelectrode of the third transistor is coupled to the first pull-downnode; and wherein a gate of the fourth transistor is coupled to thefirst signal input terminal, a first electrode of the fourth transistoris coupled to the fourth voltage terminal, and a second electrodethereof is coupled to the first pull-down node.

Optionally, the second pull-down control sub-circuit comprises a fifthtransistor, a sixth transistor, and a seventh transistor: wherein a gateof the fifth transistor is coupled to the first clock signal terminal, afirst electrode of the fifth transistor is coupled to the third voltageterminal, and a second electrode thereof is coupled to a first electrodeof the sixth transistor; wherein a gate of the sixth transistor iscoupled to the second clock signal terminal, and a second electrode ofthe sixth transistor is coupled to the second pull-down node; andwherein a gate of the seventh transistor is coupled to the first signalinput terminal, a first electrode of the seventh transistor is coupledto the fourth voltage terminal, and a second electrode thereof iscoupled to the second pull-down node.

Optionally, the first pull-down sub-circuit comprises: an eighthtransistor, wherein a gate of the eighth transistor is coupled to thefirst pull-down node, a first electrode of the eighth transistor iscoupled to the fourth voltage terminal, and a second electrode thereofis coupled to the signal output terminal of the control circuit.

Optionally, the second pull-down module comprises: a ninth transistor,wherein a gate of the ninth transistor is coupled to the secondpull-down node, a first electrode of the ninth transistor is coupled tothe fourth voltage terminal, and a first second electrode thereof iscoupled to the signal output terminal of the control circuit.

Optionally, the reset module comprises: a tenth transistor, where a gateof the tenth transistor is coupled to the second signal input terminal,a first electrode of the tenth transistor is coupled to the firstvoltage terminal, and a second electrode thereof is coupled to thesecond pull-down node.

Optionally, the second pull-up control sub-circuit comprises an eleventhtransistor and a twelfth transistor; wherein a gate of the eleventhtransistor is coupled to the third voltage terminal, a first electrodeof the eleventh transistor is coupled to the signal output terminal ofthe control circuit, and a second electrode thereof is coupled to thepull-up control node; and wherein a gate of the twelfth transistor iscoupled to the second voltage terminal, a first electrode of the twelfthtransistor is coupled to the signal output terminal of the controlcircuit, and a second electrode thereof is coupled to the pull-upcontrol node.

Optionally, the pull-up sub-circuit comprises a thirteenth transistorand a storage capacitor; wherein a gate of the thirteenth transistor iscoupled to the pull-up control node, a first electrode of the thirteentransistor is coupled to the third clock signal terminal, and a secondelectrode thereof is coupled to the signal output terminal of the buffercircuit: and wherein one terminal of the storage capacitor is coupled tothe gate of the thirteenth transistor, and another terminal thereof iscoupled to the second electrode of the thirteenth transistor.

Optionally, the third pull-down sub-circuit comprises: a fourteenthtransistor, wherein a gate of the fourteenth transistor is coupled tothe first pull-down node, a first electrode of the fourteenth transistoris coupled to the fourth voltage terminal, and a second electrodethereof is coupled to the signal output terminal of the buffer circuit.

Optionally, the fourth pull-down sub-circuit comprises: a fifteenthtransistor, wherein a gate of the fifteenth transistor is coupled to thesecond pull-down node, a first electrode of the fifteenth transistor iscoupled to the fourth voltage terminal, and a second electrode thereofis coupled to the signal output terminal of the buffer circuit.

In another embodiment, there is provided a gate drive circuit,comprising: Q groups of shift register units cascaded in series, one ofthe Q groups of shift register units cascaded in series comprising Sshift register units cascaded in series, each of the S shift registerunits for outputting scan signals to M gate lines, and S×M clock signallines, M clock signal lines of which is coupled to one of the S shiftregister units in each of the Q groups of shift register units, Q, S andM are integer, S≥2, M≥2; wherein each of the S shift register unitscomprises a control circuit configured to output a control signal, Mbuffer circuits coupled to the control circuit, and S×M buffer circuitscoupled to the S×M clock signal lines for sequentially providing S×Mclock signals respectively in one group of the Q groups of shiftregister units cascaded in series, wherein each of the M buffer circuitsis configured to be controlled by the control signal and one of the Mclock signals provided by the M clock signal lines to output a scansignal to a gate line of the M gate lines.

Optionally, the S×M clock signals sequentially from 1^(st) clock signalto the S×M-th clock signal are provided with a time-delay between anypair of subsequent clock signals.

Optionally, the time-delay equals to 1/S×M of one period of each clocksignal.

Optionally, the S×M clock signals sequentially from 1st clock signal tothe S×M-th clock signal comprise a plurality of groups of clock signals,a time-delay is provided between two time-sequential groups of clocksignals of the plurality of groups of clock signals, and clock signalsin each of the plurality of groups of clock signals are in phase.

Optionally, each of the plurality of groups of clock signals comprisestwo clock signals of the S×M clock signals.

Optionally, each of the plurality of groups of clock signals comprisesfour clock signals of the S×M clock signals.

Optionally, wherein S=3, Q=4.

Optionally, wherein S=4, Q=2.

As shown in Figs, there is provided a gate drive circuit for outputtingscan signals to the gate lines (G1, G2, . . . ). The gate drive circuitmay include a number of N cascaded shift register units 10, as shown inFIG. 1. Every number of S successive cascaded shift register units 10may constitute a drive group 01, and in the example shown in FIG. 1 twoshift register units 10 constitute a drive group 01, where N>S≥1 andboth N and S are positive integers.

In particular, each shift register unit 10 may include a control circuitSR and at least two buffer circuits BF coupled to the control circuitSR. A signal output terminal VOUT of each buffer circuit BF may becoupled to a row of gate line which is labeled Gate. Each shift registerunit 10 may include a number of M buffer circuits (BF_1, BF_2 . . .BF_M), where M≥2 and M is a positive integer.

The clock signal terminals CK of every two buffer circuits BF in thesame drive group 01 may be coupled to different system clock signalterminals (CLK1, CLK2, . . . or CLK-U, where U≥2 and U is a positiveinteger). As such, in a forward scan mode for example, when differentsignals are input from the above system clock signal terminals (CLK1,CLK2, . . . , CLK-U), the gate scan signals output from top to bottom bythe buffer circuits BF in the same drive group 01 in turn may constitutea certain phase difference so that the gate lines coupled to therespective buffer circuits BF in the same drive group 01 can be turnedon in a line-by-line manner.

Alternatively, when at least two of the above system clock signalterminals (CLK1, CLK2, . . . , CLK-U) that are coupled to the buffercircuits BF supply the same clock signals, the clock signal terminals CKof at least two buffer circuits BF in the same drive group 01 mayreceive the same clock signals. Thus, the gate scan signals output fromthe signal output terminals VOUT of the above at least two buffercircuits BF may be synchronized so that the gate lines respectivelycoupled to the above at least two buffer circuits BF can be scannedsimultaneously.

In addition, the clock signal terminals of the control circuit SR andthose of the buffer circuits BF in the same shift register unit 10 maybe coupled to different system clock signal terminals so that the inputsignals to the first signal terminal INPUT1 and to the second signalterminal INPUT2 of the control circuit SR may both constitute a phasedifference from the output signals of the signal output terminals VOUTof the buffer circuits BF, thereby achieving the shift register of thegate scan signals.

Further, the N shift register units 10 may be cascaded with each otherto form the gate drive circuit according to the following cascade mode.A first signal input terminal INPUT1 of the control circuit SR of thefirst stage shift register unit 10 may be coupled to a start signalterminal STV. The start signal terminal STV may be configured to input astart signal to drive the gate drive circuit to enter an operatingstate. Aside from the first stage shift register unit 10, the firstsignal input terminal INPUT1 of the control circuit SR of each of theother shift register units 10 may be coupled to the signal outputterminal VOUT of a buffer circuit BF of the (N−1)th stage shift registerunit 10, where N represents a variable denoting the instant stage shiftregister unit 10 and (N−1) denotes the immediate previous stage shiftregister unit 10.

Namely, the gate scan signal output from the signal output terminal VOUTof the buffer circuit BF of the previous stage shift register unit 10may serve as the input signal of the control circuit SR of the nextstage shift register unit 10.

Furthermore, the second signal input terminal INPUT2 of the controlcircuit SR of each shift register unit 10 may be coupled to the signaloutput terminal of a buffer circuit BF of the (N+2)th stage shiftregister unit 10 except for the last two stages of shift register units10, where N represents a variable denoting the instant stage shiftregister unit 10 and (N+2) denotes the later stage shift register unit10 that is 2 stages from the instant stage.

Meanwhile, the second signal input terminal INPUT2 of either of thecontrol circuits SR of the last two stages of shift register units 10may be coupled to a reset signal terminal REST. The reset signalterminal REST may be configured to output a reset signal to reset thelast two stages of shift register units 10.

Simply put, each shift register unit includes a control circuit and atleast two buffer circuits coupled to the control circuit, and the clocksignal terminals of every two buffer circuits in the same drive groupare coupled to different system clock signal terminals, and those of thecontrol circuit and of the buffer circuits in the same shift registerunit are coupled to different system clock signal terminals. Thus, theclock signal terminals of every two buffer circuits in each drive groupcan be made to receive different clock signals when the resolution ofthe picture to be displayed is equivalent to the intrinsic resolution ofthe display device. As such, a start signal may be fed to the startsignal terminal, and the gate scan signals sequentially output from thesignal output terminals of the buffer circuits from top to bottom inturn may constitute a certain phase difference, so that all rows of gatelines can be scanned progressively. Therefore, the display deviceemploying the gate drive circuit can display contents at its intrinsicresolution.

Alternatively, if the resolution of the picture to be displayed is lowerthan the intrinsic resolution of the display device, the clock signalterminals of at least two buffer circuits in any one of the shiftregister units can be made to receive the same clock signals. As such,the gate scan signals output from the signal output terminals of theabove at least two buffer circuits may be synchronized so that the gatelines respectively coupled to the two buffer circuits can be scannedsimultaneously. Hence, the display device employing the gate drivecircuit can display a picture at a resolution lower than its intrinsicresolution, leading to the purpose of reducing the display powerconsumption.

In the case where the resolution of the picture to be displayed is lowerthan the intrinsic resolution of the display device, a detaileddescription is provided below as to the specific structure of the gatedrive circuit used to convert the resolution of the display device,where the intrinsic resolution of the display device as described aboveis 8K for example.

In this embodiment, the display device employing the above gate drivecircuit has an intrinsic resolution of 8K, and the display device alsocan convert its resolution from 8K to 4K or from 8K to 2K.

Each drive group 01 of the gate drive circuit may be coupled to a numberof 12 gate lines. As shown in FIG. 2, each of the drive groups 01 mayinclude a first shift register unit 10_1, a second shift register unit10_2, and a third shift register unit 10_3 successively cascaded.

Each of first shift register unit 10_1, the second shift register unit10_2, and the third shift register unit 10_3 may include a first buffercircuit BF_1, a second buffer circuit BF_2, a third buffer circuit BF_3,and a fourth buffer circuit BF_4.

The clock signal terminals CK of the first buffer circuit BF_1, thesecond buffer circuit BF_2, the third buffer circuit BF_3, and thefourth buffer circuit BF_4 in the first shift register unit 10_1 may becoupled to a first system clock signal CLK1, a second system clocksignal CLK2, a third system clock signal CLK3, and a fourth system clocksignal CLK4, respectively.

The clock signal terminals CK of the first buffer circuit BF_1, thesecond buffer circuit BF_2, the third buffer circuit BF_3, and thefourth buffer circuit BF_4 in the second shift register unit 10_2 may becoupled to a fifth system clock signal CLK5, a sixth system clock signalCLK6, a seventh system clock signal CLK7, and an eighth system clocksignal CLK5, respectively.

The clock signal terminals CK of the first buffer circuit BF_1, thesecond buffer circuit BF_2, the third buffer circuit BF_3, and thefourth buffer circuit BF_4 in the third shift register unit 10_3 may becoupled to a ninth system clock signal CLK9, a tenth system clock signalCLK10, an eleventh system clock signal CLK11, and a twelfth system clocksignal CLK12, respectively.

The control circuit SR of each of the first shift register unit 10_1,the second shift register unit 10_2, and the third shift register unit10_3 may have two clock signal terminals, i.e., a first clock signalterminal CK1 and a second clock signal terminal CK2.

The first clock signal terminal CK1 and the second clock signal terminalCK2 of the control circuit SR in the first shift register unit 10_1 maybe coupled to the eighth system clock signal terminal CLK8 and the ninthsystem clock signal terminal CLK9, respectively. The first clock signalterminal CK1 and the second clock signal terminal CK2 of the controlcircuit SR in the second shift register unit 10_2 may be coupled to thetwelfth system clock signal terminal CLK12 and the first system clocksignal terminal CLK1, respectively. The first clock signal terminal CK1and the second clock signal terminal CK2 of the control circuit SR inthe third shift register unit 10_3 may be coupled to the fourth systemclock signal terminal CLK4 and the fifth system clock signal terminalCLK5, respectively.

As described above, each one of the first shift register unit 10_1, thesecond shift register unit 10_2, and the third shift register unit 10_3is coupled to a sequence of four gate lines. Therefore, adopting thesignal timing shown in FIG. 3, the clock signals input from the firstsystem clock signal terminal CLK1, the second system clock signalterminal CLK2, the third system clock signal terminal CLK3, the fourthsystem clock signal terminal CLK4, the fifth system clock signalterminal CLK5, the sixth system clock signal terminal CLK6, the seventhsystem clock signal terminal CLK7, the eighth system clock signalterminal CLK8, the ninth system clock signal terminal CLK9, the tenthsystem clock signal terminal CLK0, the eleventh clock signal terminalCLK11, and the twelfth system clock signal terminal CLK12 in turn mayconstitute a certain phase difference.

Note, the phase difference mentioned above can be set according toactual needs of the user. As shown in FIG. 3, for example, when the highlevel duration of the clock signal is 5H, the time difference betweentwo adjacent clock signals may be 1H while the overlap portion may be4H, where H represents the scan duration of one row of pixels, namelythe ratio of the scan duration of one image frame to the total number ofgate lines.

For example, with reference to the drive group 01 coupled to the gatelines (G1-G12), the signal output terminal VOUT of the first buffercircuit BF_1 of the first shift register unit 10_1 that is coupled tothe first system clock signal terminal CLK1 may output a gate scansignal to gate line G1. Next, gate lines G2-G12 may sequentially receivegate scan signals output from their respective coupled output terminalsVOUT of the buffer circuits. Thus, the above gate lines G1 to G12 can bescanned line by line.

Furthermore, since from top to bottom the last shift register unit 10 inthe previous drive group 01 is cascaded with the first shift registerunit 10 in the next drive group 01, the above mentioned phase differencealso may be present between the output gate scan signal of the signaloutput terminal VOUT of the last buffer circuit of the last shiftregister unit 10 in the previous drive group 01 and that of the signaloutput terminal VOUT of the first buffer circuit of the first shiftregister unit 10 in the next drive group 01. Thus, when the forward scanmode is adopted, the scan signals would be sequentially input to thegate lines from top to bottom, and so the subpixels can be turned on ina line-by-line manner, leading to a full display of the picture. In thiscase, the display device having the above-described gate drive circuitcan display at its intrinsic resolution, since all rows of subpixels areswitched on a line-by-line basis. That is, when the above intrinsicresolution is 8K and the timing signal as shown in FIG. 3 is adopted,the display device may display the picture at 8K resolution.

Alternatively, to make the display device display at 4K resolution, thetiming signal as shown in FIG. 4 may be used. The clock signals inputfrom the first system clock signal terminal CLK1, the third system clocksignal terminal CLK3, the fifth system clock signal terminal CLK5, theseventh system clock signal terminal CLK7, the ninth system clock signalterminal CLK9, and the eleventh system clock signal terminal CLK11 inturn may constitute a certain phase difference. As shown in FIG. 4, forexample, when the high level duration of the clock signal is 5H, thetime difference between two adjacent different clock signals may be 2Hwhile the overlap portion may be 3H.

The output signal of the first system clock signal CLK1 may be the sameas that of the second system clock signal terminal CLK2. The outputsignal of the third system clock signal terminal CLK3 may be the same asthat of the fourth system clock signal terminal CLK4. The output signalof the fifth system clock signal terminal CLK5 may be the same as thatof the sixth system clock signal terminal CLK6. The output signal of theseventh system clock signal terminal CLK7 may be the same as that of theeighth system clock signal terminal CLK8. The output signal of the ninthsystem clock signal terminal CLK9 may be the same as that of the tenthsystem clock signal terminal CLK10. The output signal of the eleventhsystem clock signal terminal CLK11 may be the same as that of thetwelfth system clock signal terminal CLK12.

Thus, with respect to the drive group 01 coupled to the gate lines(G1-G12), gate lines G1 and G2 may receive their gate scan signalssimultaneously. Likewise, gate lines G3 and G4 may receive their gatescan signals simultaneously; G5 and G6 may receive their gate scansignals simultaneously: G7 and G8 may receive their gate scan signalssimultaneously: G9 and G10 may receive their gate scan signalssimultaneously; and G11 and G12 may receive their gate scan signalssimultaneously. Accordingly, for the entire army substrate under theforward scan mode for example, every two successive rows of sub-pixelsarranged in order from top to bottom may be switched on simultaneously,and every two sub-pixels which spread in these two rows and are locatedin one same column may receive the same data signal and so may displaythe same greyscale. As a result, the display device having theabove-described gate drive circuit may display a resolution of one-halfof the intrinsic resolution 8K, i.e., 4K.

Alternatively, in order to further reduce the resolution so that thedisplay device can convert to a 2K resolution, a timing signal as shownin FIG. 5 may be used. The clock signals input from the first systemclock signal terminal CLK1, the fifth system clock signal terminal CLK5,and the ninth system clock signal terminal CLK9 in turn may constitute acertain phase difference. As shown in FIG. 5, for example, when the highlevel duration of the clock signal is 5H, the time difference betweentwo adjacent different clock signals may be 5H while there is nooverlap.

As such, the output signals of the first system clock signal terminalCLK1, the second system clock signal terminal CLK2, the third systemclock signal terminal CLK3, and the fourth system clock signal terminalCLK4 may be the same as one another. The fifth system clock signalterminal CLK5, the sixth system clock signal terminal, the seventhsystem clock signal terminal CLK7, and the eighth system clock signalterminal CLK8 may output the same signals. Likewise, the output signalsof the ninth system clock signal terminal CLK9, the tenth system clocksignal terminal CLK10, the eleventh system clock signal terminal CLK11,and the twelfth system clock signal terminal CLK12 may be the same aseach other.

Thus, with respect to the drive group 01 coupled to the gate lines(G1-G12), gate lines G1, G2. G3, and G4 may receive their gate scansignals simultaneously, gate lines G5, G6, G7, and G8 may receive theirgate scan signals simultaneously, and, likewise, gate lines G9, G10,G11, and G12 may receive their gate scan signals simultaneously.Accordingly, for the entire array substrate under the forward scan modefor example, every four successive rows of sub-pixels arranged in orderfrom top to bottom may be turned on simultaneously, and every foursub-pixels that spread among these four rows respectively and that arelocated in one same column may receive the same data signal and so maydisplay the same greyscale. As a result, the display device having theabove-described gate drive circuit may display a resolution of onequarter of the intrinsic resolution 8K, i.e., 2K.

As described above, the display device having the gate drive circuitwould be able to convert its display resolution from the intrinsicresolution 8K to 4K or from 8K to 2K, by controlling the output signalsof the system clock signal terminals. Thus, when the resolution of thepicture to be displayed is lower than its intrinsic resolution, thedisplay device can display the screen at a resolution of 4K or 2K so asto reduce the power consumption.

In this embodiment, the display device employing the above gate drivecircuit can convert its resolution from the intrinsic resolution 8K to4K.

Each drive group 01 of the gate drive circuit may be coupled to a numberof 8 gate lines. Referring now to FIG. 6, each of the drive groups 01 asdescribed above may include a first shift register unit 10_1, a secondshift register unit 10_2, a third shift register unit 10_3, and a fourthshift register unit 10_4 cascaded successively.

Each of first shift register unit 10_1, the second shift register unit10_2, the third shift register unit 10_3, and the fourth shift registerunit 10_4 may include a first buffer circuit BF_1 and a second buffercircuit BF_2.

The clock signal terminals CK of the first buffer circuit BF_1 and thesecond buffer circuit BF_2 in the first shift register unit 10_1 may becoupled to a first system clock signal terminal CLK1 and a second systemclock signal terminal CLK2, respectively.

The clock signal terminals CK of the first buffer circuit BF_1 and thesecond buffer circuit BF_2 in the second shift register unit 10_2 may becoupled to a third system clock signal terminal CLK3 and a fourth systemclock signal terminal CLK4, respectively.

The clock signal terminals CK of the first buffer circuit BF_1 and thesecond buffer circuit BF_2 in the third shift register unit 10_3 may becoupled to a fifth system clock signal terminal CLK5 and a sixth systemclock signal terminal CLK6, respectively.

The clock signal terminals CK of the first buffer circuit BF_1 and thesecond buffer circuit BF_2 in the fourth shift register unit 104 may becoupled to a seventh system clock signal terminal CLK7 and an eighthsystem clock signal terminal CLK8, respectively.

The control circuit SR of each of the first shift register unit 10_1,the second shift register unit 10_2, and the third shift register unit10_3 may have two clock signal terminals, i.e., a first clock signalterminal CK1 and a second clock signal terminal CK2.

The first clock signal terminal CK1 and the second clock signal terminalCK2 of the control circuit SR in the first shift register unit 10_1 maybe coupled to the fourth system clock signal terminal CLK4 and the fifthsystem clock signal terminal CLK5, respectively. The first clock signalterminal CK1 and the second clock signal terminal CK2 of the controlcircuit SR in the second shift register unit 10_2 may be coupled to thesixth system clock signal terminal CLK6 and the seventh system clocksignal terminal CLK7, respectively. The first clock signal terminal CK1and the second clock signal terminal CK2 of the control circuit SR inthe third shift register unit 10_3 may be coupled to the eighth systemclock signal terminal CLK8 and the first system clock signal terminalCLK1, respectively. And, the control circuit SR of the fourth shiftregister unit 10_4 may be coupled to the second system clock signalterminal CLK2 and the third system clock signal terminal CLK3,respectively.

As described above, each one of the first shift register unit 10_1, thesecond shift register unit 10_2, the third shift register unit 10_3, andthe fourth shift register unit 10_4 is coupled to a consecutive sequenceof two gate lines. Therefore, adopting the clock signal timing shown inFIG. 7, the clock signals input from the first system clock signalterminal CLK1, the second system clock signal terminal CLK2, the thirdsystem clock signal terminal CLK3, the fourth system clock signalterminal CLK4, the fifth system clock signal terminal CLK5, the sixthsystem clock signal terminal CLK6, the seventh system clock signalterminal CLK7, and the eighth system clock signal terminal CLK8 in turnmay constitute a certain phase difference.

For example, with respect to the drive group 01 coupled to the gatelines (G1-G8), the signal output terminal VOUT of the first buffercircuit BF_1 in the first shift register unit 10_1 that is coupled tothe first system clock signal terminal CLK1 may output a gate scansignal to gate line G1. Next, gate lines G2-G8 may sequentially receivetheir gate scan signals output from their respective coupled outputterminals VOUT of the buffer circuits. Thus, the above gate lines G1 toG8 can be scanned line by line.

In the same manner as in Embodiment 1, the above phase difference alsomay be present between the output gate scan signal of the signal outputterminal VOUT of the last buffer circuit of the last shift register unit10 in the previous drive group 01 and that of the signal output terminalVOUT of the first buffer circuit of the first shift register unit 10 inthe next drive group 01. Thus, when the forward scan mode is adopted,the scan signals may sequentially be input to the gate lines from top tobottom, and so the subpixels can be switched on in a line-by-linemanner, leading to a fill display of the picture. In this case, thedisplay device having the above-described gate drive circuit can displayat its intrinsic resolution, since all rows of subpixels are switched online by line. That is, when the above intrinsic resolution is 8K and thetiming signal as shown in FIG. 7 is adopted, the display device maydisplay the picture at the 8K resolution.

Alternatively, to make the display device display at 4K resolution, thetiming signal as shown in FIG. 8 may be used. Accordingly, the outputclock signals of the first system clock signal terminal CLK1, the thirdsystem clock signal terminal CLK3, the fifth system clock signalterminal CLK5, and the seventh system clock signal terminal CLK7 in turnmay constitute a certain phase difference.

The output signal of the first system clock signal CLK1 may be the sameas that of the second system clock signal terminal CLK2. The outputsignal of the third system clock signal terminal CLK3 may be the same asthat of the fourth system clock signal terminal CLK4. The output signalof the fifth system clock signal terminal CLK5 may be the same as thatof the sixth system clock signal terminal CLK6. The output signal of theseventh system clock signal terminal CLK7 may be the same as that of theeighth system clock signal terminal CLK8.

Thus, with respect to the drive group 01 coupled to the gate lines(G1-G8), gate lines G1 and G2 may receive their gate scan signalssimultaneously. Likewise, gate lines G3 and G4 may receive their gatescan signals simultaneously; G5 and G6 may receive their gate scansignals simultaneously; and G7 and G8 may receive their gate scansignals simultaneously. Accordingly, for the entire array substrateunder the forward scan mode for example, every two successive rows ofsub-pixels arranged in order from top to bottom may be switched onsimultaneously, and every two sub-pixels which spread in these two rowsrespectively and are located in one same column may receive the samedata signal and so may display the same greyscale. As a result, thedisplay device having the above-described gate drive circuit may displaya resolution of one-half of the intrinsic resolution 8K, i.e., 4K.

It is noteworthy that if the intrinsic resolution is 4K and the timingsignal as shown in FIG. 7 is used for display, the display device maydisplay the screen at the resolution of 4K. Otherwise, when the timingsignal as shown in FIG. 8 is used for display, the display device maydisplay at the resolution of 2K.

Comparing the gate drive circuit provided by the example as illustratedin FIG. 6 to that provided by the example as shown in FIG. 2, it can beseen that in the solution of FIG. 6 one control circuit SR is coupled toa comparatively less number of buffer circuits BF, so that the wiringspace of the non-display area can be reduced, which is advantageous tosatisfying the design requirements of ultra-narrow frame.

Hereinafter, the specific configuration of the control circuit SR andthe buffer circuit BF in any one of the shift register units 01 shown inFIG. 2 or FIG. 6 will be described in greater detail.

Referring now to FIG. 9, in particular, the control circuit SR mayinclude a first pull-up control module 20, a first pull-down controlmodule 30, a second pull-down control module 31, a first pull-downmodule 40, a second pull-down module 41, and a reset module 50.

The first pull-up control module 20 may be coupled to a first signalinput terminal INPUT1, a signal output terminal SOUT of the controlcircuit SR, and a first voltage terminal VDD. The first pull-up controlmodule 20 may be configured to output a signal of the first voltageterminal VDD to the signal output terminal SOUT of the control circuitSR under the control of the first signal input terminal INPUT1. Thefirst voltage terminal VDD may be configured to output a constant highlevel.

Typically, the first pull-up control module 20 may include a firsttransistor M1. A gate of the first transistor M1 may be coupled to thefirst signal input terminal INPUT1, a first electrode of the firsttransistor M1 may be coupled to the first voltage terminal VDD, and asecond electrode may be coupled to the signal output terminal SOUT ofthe control circuit SR.

The first pull-down control module 30 may be coupled to the first clocksignal terminal CK1, the second clock signal terminal CK2, the firstsignal input terminal INPUT1, a second voltage terminal VDD_E, a fourthvoltage terminal VGL, and a first pull-down node PD1. The firstpull-down node PD1 may be used to provide an output terminal SRST_E forthe buffer circuits BF.

As such, the first pull-down control module 30 may be configured tooutput a voltage of the second voltage terminal VDD_E to the firstpull-down node PD1 under the control of the first clock signal terminalCK1 and the second clock signal terminal CK2. Or, the first pull-downcontrol module 30 may be used to output a voltage of the fourth voltageterminal VGL to the first pull-down node PD1 under the control of thefirst signal input terminal INPUT1.

Typically, the first pull-down control module 30 may include a secondtransistor M2, a third transistor M3, and a fourth transistor M4.

A gate of the second transistor M2 may be coupled to the first clocksignal terminal CK1, a first electrode of the second transistor M2 maybe coupled to the second voltage terminal VDD_E, and a second electrodemay be coupled to a first electrode of the third transistor M3.

A gate of the third transistor M3 may be coupled to the second clocksignal terminal CK2, and a second electrode may be coupled to the firstpull-down node PD1.

A gate of the fourth transistor M4 may be coupled to the first signalinput terminal INPUT1, a first electrode of the fourth transistor M4 maybe coupled to the fourth voltage terminal VGL, and a second electrodemay be coupled to the first pull-down node PD1.

The second pull-down control module 31 may be coupled to the first clocksignal terminal CK1, the second clock signal terminal CK2, the firstsignal input terminal INPUT1, a third voltage terminal VDD_O, the fourthvoltage terminal VGL, and a second pull-down node PD2. The secondpull-down node PD2 may be used to provide an output terminal SRST_O forthe buffer circuits BF.

As such, the second pull-down control module 31 may be configured tooutput a voltage of the third voltage terminal VDD_O to the secondpull-down node PD2 under the control of the first clock signal terminalCK1 and the second clock signal terminal CK2. Or, the second pull-downcontrol module 31 may be used to output the voltage of the fourthvoltage terminal VGL to the second pull-down node PD2 under the controlof the first signal input terminal INPUT1.

Typically, the second pull-down control module 31 may comprise a fifthtransistor M5, a sixth transistor M6, and a seventh transistor M7.

A gate of the fifth transistor M5 may be coupled to the first clocksignal terminal CK1, a first electrode of the fifth transistor M5 may becoupled to the third voltage terminal VDD_O, and a second electrode maybe coupled to a first electrode of the sixth transistor M6.

A gate of the sixth transistor M6 may be coupled to the second clocksignal terminal CK2, and a second electrode may be coupled to the secondpull-down node PD2.

A gate of the seventh transistor M7 may be coupled to the first signalinput terminal INPUT1, a first electrode of the seventh transistor M7may be coupled to the fourth voltage terminal VGL, and a secondelectrode may be coupled to the second pull-down node PD2.

Note, the above second voltage terminal VDD_E and the third voltageterminal VDD_O can alternately output a high level during a very shortperiod of time, e.g., within 1 s, so that either of the first electrodesof the second transistor M2 and the fifth transistor M5 can be preventedfrom operating under a high voltage state for a long period of timewhich may otherwise cause the threshold voltage to shift. In addition, aconstant low level may be input to the fourth voltage terminal VGL.

The first pull-down module 40 may be coupled to the first pull-down nodePD1, the signal output terminal SOUT of the control circuit SR, and thefourth voltage terminal VGL The first pull-down module 40 may beconfigured to pull a voltage of the signal output terminal SOUT to thevoltage of the fourth voltage terminal VGL under the control of thefirst pull-down node PD1.

Typically, the first pull-down module 40 may comprise an eighthtransistor M8. A gate of the eighth transistor M8 may be coupled to thefirst pull-down node PD1, a first electrode of the eighth transistor M8may be coupled to the fourth voltage terminal VGL and a second electrodemay be coupled to the signal output terminal SOUT of the control circuitSR.

The second pull-down module 41 may be coupled to the second pull-downnode PD2, the signal output terminal SOUT of the control circuit SR, andthe fourth voltage terminal VGL. The second pull-down module 41 may beconfigured to pull down the voltage of the signal output terminal SOUTto the voltage of the fourth voltage terminal VGL under the control ofthe second pull-down node PD2.

Typically, the second pull-down module 41 may comprise a ninthtransistor M9. A gate of the ninth transistor M9 may be coupled to thesecond pull-down node PD2, a first electrode of the ninth transistor M9may be coupled to the fourth voltage terminal VGL, and a first electrodemay be coupled to the signal output terminal SOUT of the control circuitSR.

Furthermore, the reset module 50 may be coupled to a second signal inputterminal INPUT2, the first voltage terminal VDD, and the secondpull-down node PD2. The reset module 50 may be configured to transferthe voltage of the first voltage terminal VDD to the second pull-downnode PD2 under the control of the second signal input terminal INPUT2.

Typically, the reset module 50 may comprise a tenth transistor M10,where a gate of the tenth transistor M10 may be coupled to the secondsignal input terminal INPUT2, a first electrode of the tenth transistorM10 may be coupled to the first voltage terminal VDD, and a secondelectrode may be coupled to the second pull-down node PD2.

Referring now to FIG. 10, each buffer circuit BF in the shift registerunit 10 may include a pull-up module 60, a second pull-up control module21, a third pull-down module 70, and a fourth pull-down module 71.

The second pull-up control module 21 may be coupled to a pull-up controlnode PU, the second voltage terminal VDD_E, the third voltage terminalVDD_O, and the signal output terminal SOUT of the control circuit SR.The second pull-up control module 21 may be configured to turn on andoutput a signal of the signal output terminal SOUT to the pull-upcontrol node PU under the control of the second voltage terminal VDD_Eand the third voltage terminal VDD_O.

Typically, the second pull-up control module 21 may comprise an eleventhtransistor M11 and a twelfth transistor M12. A gate of the eleventhtransistor M11 may be coupled to the third voltage terminal VDD_O, afirst electrode of the eleventh transistor M11 may be coupled to thesignal output terminal SOUT of the control circuit SR, and a secondelectrode may be coupled to the pull-up control node PU.

A gate of the twelfth transistor M12 may be coupled to the secondvoltage terminal VDD_E, a first electrode of the twelfth transistor M12may be coupled to the signal output terminal SOUT of the control circuitSR, and a second electrode may be coupled to the pull-up control nodePU.

The pull-up module 60 may be coupled to the pull-up control node PU, athird clock signal terminal CK3, and the signal output terminal VOUT ofthe buffer circuit BF. The pull-up module 60 may be used to output asignal of the third clock signal terminal CK3 to the signal outputterminal VOUT of the buffer circuit BF under the control of the pull-upcontrol node PU.

In order to distinguish from the clock signal terminals of the controlcircuit SR, i.e., the above-described first clock signal terminal CK1and second clock signal terminal CK2, the clock signal terminal CK ofthe buffer circuit BF as shown in FIG. 2 or FIG. 6 is herein referred toas the third clock signal terminal CK3.

Typically, the pull-up module 60 may include a thirteenth transistor M13and a storage capacitor C. A gate of the thirteenth transistor M13 maybe coupled to the pull-up control node PU, a first electrode of thethirteenth transistor M13 may be coupled to the third clock signalterminal CK3, and a second electrode may be coupled to the signal outputterminal VOUT of the buffer circuit BF.

One terminal of the storage capacitor C may be coupled to the gate ofthe thirteenth transistor M13, while the other terminal thereof may becoupled to the second electrode of the thirteenth transistor M13.

The third pull-down module 70 may be coupled through the interfaceSRST_E to the first pull-down node PD1. The third pull-down module 70further may be coupled to the fourth voltage terminal VGL and the signaloutput terminal VOUT of the buffer circuit BF. The third pull-downmodule 70 may be configured to pull down the voltage of the signaloutput terminal VOUT to the voltage of the fourth voltage terminal VGLunder the control of the first pull-down node PD1.

In particular, the third pull-down module 70 may include a fourteenthtransistor M14, where a gate of the fourteenth transistor M14 may becoupled to the first pull-down node PD1, a first electrode of thefourteenth transistor M14 may be coupled to the fourth voltage terminalVGL, and a second electrode may be coupled to the signal output terminalVOUT.

The fourth pull-down module 71 may be coupled through the interfaceSRST_E to the second pull-down node PD2. The fourth pull-down module 71further may be coupled to the fourth voltage terminal VGL and the signaloutput terminal VOUT of the buffer circuit BF. The fourth pull-downmodule 71 may be configured to pull down the voltage of the signaloutput terminal VOUT to the voltage of the fourth voltage terminal VGLunder the control of the second pull-down node PD2.

Typically, the fourth pull-down module 71 may comprise a fifteenthtransistor M15. A gate of the fifteenth transistor M15 may be coupled tothe second pull-down node PD2, a first electrode of the fifteenthtransistor M15 may be coupled to the fourth voltage terminal VGL, and asecond electrode may be coupled to the signal output terminal VOUT.

Note, in the present disclosure the types of the above-mentionedtransistors are not limited. For example, the above transistors can allbe N type transistors or P type transistors. In the above descriptionthe first electrode of a transistor may be the source and the secondelectrode the drain; or the first electrode may be the drain and thesecond electrode the source.

Further, the control circuit SR as shown in FIG. 9 can be connected tothe buffer circuit as shown in FIG. 10 to form the circuit structure asillustrated in FIG. 11. Hereinafter, the drive method for any of theshift register units 10 shown in FIG. 2 will be described in detail inbased on the circuit configuration shown in FIG. 11 where theabove-described transistors are all N type transistors for example.

With a display device that employs the gate drive circuit as illustratedin FIG. 2 and that has an intrinsic resolution of 8K, the signal timingas shown in FIG. 3 may be adopted when the display device needs todisplay contents at its intrinsic resolution. Accordingly, the clocksignals input from the first system clock signal terminal CLK1, thesecond system clock signal terminal CLK2, the third system clock signalterminal CLK3, the fourth system clock signal terminal CLK4, the fifthsystem clock signal terminal CLK5, the sixth system clock signalterminal CLK6, the seventh system clock signal terminal CLK7, the eighthsystem clock signal terminal CLK5, the ninth system clock signalterminal CLK9, the tenth system clock signal terminal CLK10, theeleventh clock signal terminal CLK11, and the twelfth system clocksignal terminal CLK12 in turn may constitute a certain phase difference.

On basis of the above, a drive method within a single image frame forthe first shift register unit 10_1 in drive group 01 coupled to the gatelines (G1-G12) is described in detail as follows.

One image frame may include a first stage T1, a second stage T2, and athird stage T3, in particular, as shown in FIG. 3 or FIG. 4 or FIG. 5.

First, at the first stage T1, the first signal input terminal INPUT1 ofthe control circuit SR of the first shift register unit 10_1 may receivea start signal from the start signal terminal STV. At this point, asshown in FIG. 11, the first transistor M1 may be switched on and so mayoutput a high level of the first voltage terminal VDD to the signaloutput terminal SOUT of the control circuit SR which may furthertransfer the above high level to the first buffer circuit BF_1.

Then, the eleventh transistor M11 and the twelfth transistor M12 in thefirst buffer circuit BF_1 may be switched on and so may transfer theoutput high level of the signal output terminal SOUT to the storagecapacitor C and to the gate of the thirteenth transistor M13. Thus, thestorage capacitor C would store the above high level. At this point, theclock signal terminal of the first buffer circuit BF_1, namely the thirdclock signal terminal CK3 may receive from the first system clock signalterminal CLK1 a low level clock signal, as shown in FIG. 3. The lowlevel may be transferred to the signal output terminal VOUT of the firstbuffer circuit BF_1 through the conducting thirteenth transistor M13. Asa result, gate line G1 coupled to this signal output terminal VOUT mayoutput a low level.

Further, as shown in FIG. 3, since the eighth system clock signalterminal CLK8 coupled to the first clock signal terminal CK1 of thecontrol circuit SR_1 and the ninth system clock signal terminal CLK9coupled to the second clock signal terminal CK2 of the control circuitSR_1 both are fed low levels, the second transistor M2, the thirdtransistor M3, the fifth transistor M5, and the sixth transistor M6 mayall be turned off.

In addition, the first signal input terminal INPUT1 may be fed a highlevel and so the fourth transistor M4 may be turned on, so that theelectric potential of the first pull-down node PD1 may be pulled down tothe low level of the fourth voltage terminal VGL, and at this point boththe eighth transistor M8 and the fourteenth transistor M14 may be turnedoff. Likewise, the first signal input terminal INPUT1 may be fed a highlevel and so the seventh transistor M7 may be turned on, so that theelectric potential of the second pull-down node PD2 may be pulled downto the low level of the fourth voltage terminal VGL, and at this pointboth the ninth transistor M9 and the fifteenth transistor M15 may beturned off. In addition, since the second signal input terminal INPUT2is fed a low level, the tenth transistor M10 may be turned off.

As described above, because at the first stage T1 the signal outputterminal VOUT of the first buffer circuit BF_1 that is coupled to gateline G1 outputs a low level, the row of pixels coupled to this gate lineG1 may not be turned on.

Next, in the second stage 12, the storage capacitor C as shown in FIG.11 may release the high level stored in the previous stage, so that theelectric potential of the pull-up control node PU may be increased andso the thirteenth transistor M13 may be switched on. At this point, thethird clock signal terminal CK3 may receive from the first system clocksignal terminal CLK1 a high level clock signal, as shown in FIG. 3,causing the signal output terminal VOUT of the first buffer circuit BF_1to output a high level to gate line G1 coupled thereto.

The other transistors are turned off or turned on in a similar manner asdescribed above and are not to be detailed again herein.

As described above, since at the second stage T2 the signal outputterminal VOUT of the first buffer circuit BF_1 that is coupled to gateline G1 outputs a high level, so that the row of pixels coupled to thisgate line G1 may be turned on.

Finally, in the third stage T3, because the eighth system clock signalterminal CLK8 coupled to the first clock signal terminal CK1 of thecontrol circuit SR_1 and the ninth system clock signal terminal CLK9coupled to the second clock signal terminal CK2 of the control circuitSR_1 both are fed high levels, the second transistor M2, the thirdtransistor M3, the fifth transistor M5, and the sixth transistor M6 mayall be turned on.

Therefore, the high level of the second voltage terminal VDD_E may betransferred to the first pull-down node PD1 through the secondtransistor M2 and the third transistor M3, causing the electricpotential of the first pull-down node PD1 to go up. At this point, theeighth transistor M8 and the fourteenth transistor M14 may both beturned on, and so the eighth transistor M8 may pull the voltage of thesignal output terminal SOUT of the control circuit SR_1 down to the lowlevel of the fourth voltage terminal VGL. As such, the thirteenthtransistor M13 may be turned off. In addition, the fourteenth transistorM14 may pull the voltage of the signal output terminal VOUT of the firstbuffer circuit BF_1 down to the low level of the fourth voltage terminalVGL.

Similarly, the high level of the third voltage terminal VDD_O may betransferred to the second pull-down node PD2 through the fifthtransistor M5 and the sixth transistor M6, causing the electricpotential of the second pull-down node PD2 to rise. At this point, theninth transistor M9 and the fifteenth transistor M15 may both be turnedon, and so the ninth transistor M9 may pull the voltage of the signaloutput terminal SOUT of the control circuit SR_1 down to the low levelof the fourth voltage terminal VGL. As such, the thirteenth transistorM13 may be turned off. In addition, the fifteenth transistor M15 maypull the voltage of the signal output terminal VOUT of the first buffercircuit BF_1 down to the low level of the fourth voltage terminal VGL.

Further, the second signal input terminal INPUT2 may be fed a high leveland so the tenth transistor M10 may be turned on, so that the voltage ofthe first voltage terminal VDD may be output to the second pull-downnode PD2, which may control the fourteenth transistor M14 and thefifteenth transistor M15 to turn on so as to reset the signal outputterminal SOUT of the control circuit SR_1.

As described above, because at the third stage T3 the voltage signaloutput terminal VOUT of the first buffer circuit BF_1 that is coupled togate line G1 is pulled down to the low level of the fourth voltageterminal VGL, the row of pixels coupled to this gate line G1 may not beturned on.

As can be concluded, the signal output terminal VOUT of the first buffercircuit BF_1 may output a gate scan signal to gate line G1 during thesecond stage T2. Since the first shift register unit 10_01 is controlledby using the clock signal as shown in FIG. 3, the first buffer circuitBF_1, the second buffer circuit BF_2, the third buffer circuit BF_3, andthe fourth buffer circuit BF_4 in the first shift register unit 10_01may output the above gate scan signal in turn to scan the gate lines G1to G4 progressively.

Therefore, for the entire array substrate under the forward scan modefor example, each and every row of subpixels from top to bottom may beturned on so that the display device having the above-described gatedrive circuit can display at its intrinsic resolution, since all rows ofsubpixels are turned on progressively. That said, when the aboveintrinsic resolution is 8K and the timing signal as shown in FIG. 3 isadopted, then the display device may display the picture at the 8Kresolution.

Alternatively, to make the display device employing the gate drivecircuit as shown in FIG. 2 display at 4K resolution, the timing signalas shown in FIG. 4 may be used. The drive method for any one of theshift register units of the gate drive circuit is as described above,and so is not to be detailed again. It can be seen from FIG. 4 thatlines G1 and G2 are scanned simultaneously, while G3 and G4 are scannedsimultaneously. Thus, for the entire array substrate under the forwardscan mode for example, every two successive rows of sub-pixels arrangedin order from top to bottom may be switched on simultaneously, and everytwo sub-pixels which spread in these two rows and which are located inone same column may receive the same data signal and so may display thesame greyscale. As a result, the display device having theabove-described gate drive circuit may display a resolution of one-halfof the intrinsic resolution 8K, namely, 4K.

Alternatively, to make the display device employing the gate drivecircuit as shown in FIG. 2 display at 2K resolution, the timing signalas shown in FIG. 5 may be used. The drive method for any one of theshift register units of the gate drive circuit is as described above,and so is not to be detailed again. It can be seen from FIG. 5 thatlines G1, G2, G3, and G4 are scanned simultaneously. Thus, for theentire array substrate under the forward scan mode for example, everyfour successive rows of sub-pixels arranged in order from top to bottommay be switched on simultaneously, and every four sub-pixels that spreadamong the four rows and that are located in one same column may receivethe same data signal and so may display the same greyscale. As a result,the display device having the above-described gate drive circuit maydisplay a resolution of one quarter of the intrinsic resolution 8K,i.e., 2K.

Of course, the foregoing description is made to illustrate the drivemethod for the first shift register unit 10_1 based on the displaydevice having the gate drive circuit as shown in FIG. 2 where thedisplay resolution converts from 8K to 4K and from 8K to 2K. So, whenthe display resolution is switched from 8K to 4K or from 4K to 2K basedon a display device having a gate drive circuit as shown in FIG. 6, thedrive method for the first shift register unit 10_1 would be the same asabove and so is not to be repeated herein.

There is also provided a display device including any of the gate drivecircuits as described above which has the same structure and advantagesas the gate drive circuits provided in the foregoing embodiments. Sincethe specific structures of the gate drive circuits have been describedin detail in the foregoing embodiments, they are not to be detailedagain herein.

In this embodiment, the display device may include at least a liquidcrystal display (LCD) device and an organic light emitting diode (OLED)display device. For example, the display device may be a liquid crystaldisplay, a liquid crystal television, a digital photo frame, a mobilephone, a tablet computer, or any other product or component equippedwith display function.

There is also provided a method of driving any of the gate drivecircuits as described above.

For example, when the display device employing the gate drive circuitdisplays contents at its intrinsic resolution, the method may includethe following process.

First, different clock signals may be input to the clock signalterminals CK of the control circuit SR and of the buffer circuits BF inthe same shift register unit 10, as shown in FIG. 1.

Then, different clock signals may be input to the clock signal terminalsCK of every two buffer circuits BF in the same drive group 01.

As such, under the forward scan mode for example, when different signalsare input from the above system clock signal terminals (CLK1, CLK2, . .. , CLK-U), the gate scan signals output from the buffer circuits BF inthe same drive group 01 may in turn constitute a certain phasedifference so that the gate lines coupled to the respective buffercircuits BF of the same drive group 01 can be turned on in aline-by-line manner. For the entire army substrate when the forward scanmode is applied, each and every row of subpixels from top to bottomwould be tuned on so that the display device having the above-describedgate drive circuit can display at its intrinsic resolution, since allrows of subpixels are turned on progressively.

Alternatively, when the display device having the gate drive circuitdisplays contents at a resolution lower than its intrinsic resolution,the above drive method may include the following process.

The same clock signals may be input to the clock signal terminals CK ofat least two buffer circuits BF in a same shift register unit 10 asshown in FIG. 1, and so the signal output terminals VOUT of the at leasttwo buffer circuits BF that receive the same clock signals may outputtheir gate scan signals simultaneously.

Meanwhile, the clock signals fed to the clock signal terminals CK of thebuffer circuits BF of every two shift register units 10 in the samedrive group 01 may be different from each other.

As such, the gate scan signals output from the signal output terminalsVOUT of the above at least two buffer circuits BF may be synchronized sothat the gate lines respectively coupled to the at least two buffercircuits BF can be scanned simultaneously. As a result, the displaydevice employing the gate drive circuit may display a picture at aresolution lower than its intrinsic resolution, leading to the purposeof reducing the display power consumption.

With reference made to the gate drive circuit as illustrated in FIG. 2,in particular, the method by which the same clock signals are fed to atleast two buffer circuits BF in the same shift register unit 10 will bedescribed as follows, where the display resolution of the display devicehaving the gate drive circuit converts from 8K to 4K, for example.

Each drive group 01 of the gate drive circuit may be coupled to a numberof 12 gate lines. As shown in FIG. 2, each of the above mentioned drivegroups 01 may include a first shift register unit 10_1, a second shiftregister unit 10_2, and a third shift register unit 10_3. Each of firstshift register unit 10_1, the second shift register unit 10_2, and thethird shift register unit 10_3 may include a first buffer circuit BF_1,a second buffer circuit BF_2, a third buffer circuit BF_3, and a fourthbuffer circuit BF_4.

In another embodiment, a method for driving a gate drive circuit, thegate drive circuit comprises Q groups of shift register units cascadedin series, one of the Q groups of shift register units cascaded inseries comprising S shift register units cascaded in series, each of theS shift register units comprises a control circuit configured to outputa control signal, M buffer circuits coupled to the control circuit, eachof the S shift register units for outputting scan signals to M gatelines, and S×M clock signal lines, M clock signal lines of which iscoupled to one of the S shift register units, Q, S and M are integer,S≥2, M≥2; the method comprising: providing S×M clock signalstime-sequentially from a 1st clock signal to a S×M-th clock signalthrough the S×M clock signal lines respectively to the S shift registerunits in each of the Q groups of shift register units; wherein providingM clock signals through the M clock signal lines to the M buffercircuits in each of the S shift register units.

Optionally, the S×M clock signals sequentially from 1st clock signal tothe S×M-th clock signal are provided with a time-delay between any pairof subsequent clock signals.

Optionally, the time-delay equals to 1/S×M of one period of each clocksignal.

Optionally, the S×M clock signals sequentially from 1st clock signal tothe S×M-th clock signal comprise a plurality of groups of clock signals,a time-delay is provided between two time-sequential groups of clocksignals of the plurality of groups of clock signals, and clock signalsin each of the plurality of groups of clock signals are in phase.

Optionally, each of the plurality of groups of clock signals comprisestwo clock signals of the S×M clock signals.

Optionally, each of the plurality of groups of clock signals comprisesfour clock signals of the S×M clock signals.

Optionally, wherein S=3, Q=4.

Optionally, wherein S=4. Q=2.

Turning to FIG. 4, the method may include inputting the same signalsfrom the first system clock signal terminal CLK1 and to the secondsystem clock signal terminal CLK2;

Inputting the same signals from the third system clock signal terminalCLK3 and to the fourth system clock signal terminal CLK4;

Inputting the same signals from the fifth system clock signal terminalCLK5 and to the sixth system clock signal terminal CLK6;

Inputting the same signals from the seventh system clock signal terminalCLK7 and to the eighth system clock signal terminal CLK8;

Inputting the same signals from the ninth system clock signal terminalCLK9 and to the tenth system clock signal terminal CLK10:

Inputting the same signals from the eleventh system clock signalterminal CLK11 and to the twelfth system clock signal terminal CLK12.

Meanwhile, the clock signals input from the first system clock signalterminal CLK1, the third system clock signal terminal CLK3, the fifthsystem clock signal terminal CLK5, the seventh system clock signalterminal CLK7, the ninth system clock signal terminal CLK9, and theeleventh system clock signal terminal CLK11 may in turn differ from oneanother by a certain phase difference.

The phase difference as mentioned above can be set according to actualneeds of the user. As shown in FIG. 4, for example, when the high levelduration of the clock signal is 5H, the time difference between twoadjacent different clock signals may be 2H while the overlap portion maybe 3H.

Thus, with respect to the drive group 01 coupled to the gate lines(G1-G12), gate lines G1 and G2 may receive their gate scan signalssimultaneously. Likewise, gate lines G3 and G4 may receive their gatescan signals simultaneously; G5 and G6 may receive their gate scansignals simultaneously; G7 and G8 may receive their gate scan signalssimultaneously; G9 and G10 may receive their gate scan signalssimultaneously: and G11 and G12 may receive their gate scan signalssimultaneously. Accordingly, for the entire array substrate under theforward scan mode for example, every two successive rows of sub-pixelsarranged in order from top to bottom may be switched on simultaneously,and every two sub-pixels that spread in these two rows and that arelocated in one same column may receive the same data signal and so maydisplay the same greyscale. As a result, the display device having theabove-described gate drive circuit may display at a resolution ofone-half of the intrinsic resolution 8K, i.e., 4K.

Alternatively, with reference to the gate drive circuit as shown in FIG.2, the method by which the same clock signals are fed to at least twobuffer circuits BF in the same shift register unit will be described asfollows, where the display resolution of the display device having thegate drive circuit converts from 8K to 2K, for example.

In particular, the above method may include the following process inconnection with FIG. 5.

The same signals may be input from the first system clock signalterminal CLK1, the second system clock signal terminal CLK2, the thirdsystem clock signal terminal CLK3, and the fourth system clock signalterminal CLK4.

The same signals may be input from the fifth system clock signalterminal CLK5, the sixth system clock signal terminal CLK6, the seventhsystem clock signal terminal CLK7, and the eighth system clock signalterminal CLK8.

The same signals may be input from the ninth system clock signalterminal CLK9, the tenth system clock signal terminal CLK10, theeleventh system clock signal terminal CLK11, and the twelfth systemclock signal terminal CLK12.

The output clock signals of the first system clock signal terminal CLK1,the fifth system clock signal terminal CLK5, and the ninth system clocksignal terminal CLK9 in turn may differ from each other by a certainphase difference. As shown in FIG. 5, for example, when the high levelduration of the clock signal is 5H, the time difference between twoadjacent different clock signals may be 5H while there is no overlap.

Thus, with respect to the drive group 01 coupled to the gate lines(G1-G12), gate lines G1, G2, G3, and G4 may receive their gate scansignals simultaneously, gate lines G5, G6, G7, and G8 may receive theirgate scan signals simultaneously, and, likewise, gate lines G9, G10,G11, and G12 may receive their gate scan signals at the same time.Accordingly, for the entire array substrate under the forward scan modefor example, every four successive rows of sub-pixels arranged in orderfrom top to bottom may be turned on simultaneously, and every foursub-pixels that spread among these four rows respectively and arelocated in one same column may receive the same data signal and so maydisplay the same greyscale. As a result, the display device having theabove-described gate drive circuit may display a resolution of onequarter of the intrinsic resolution 8K, i.e., 2K.

As described above, the display device having the gate drive circuit maybe able to convert its display resolution from its intrinsic resolution8K to 4K or from 8K to 2K, by controlling the output signals of thesystem clock signal terminals. Thus, when the resolution of the pictureto be displayed is lower than its intrinsic resolution, the displaydevice may display contents at a resolution of 4K or 2K to reduce thepower consumption.

Thus, gate drive circuits, methods of driving the same, and associateddisplay devices are provided herein. The gate drive circuit is used foroutputting scan signals to gate lines and includes a number of Ncascaded shift register units. Every number of S successive cascadedshift register units constitute a drive group, where N>S≥1 and both Nand S are positive integers. Each shift register unit includes a controlcircuit and at least two buffer circuits coupled to the control circuit.The signal output terminal of each buffer circuit is coupled to a row ofgate line. The clock signal terminals of every two buffer circuits inthe same drive group are coupled to different system clock signalterminals. Furthermore, the clock signal terminals of the controlcircuit and those of the buffer circuits in the same shift register unitare coupled to different system clock signal terminals.

Simply put, each shift register unit includes a control circuit and atleast two buffer circuits coupled to the control circuit, and the clocksignal terminals of every two buffer circuits in the same drive groupare coupled to different system clock signal terminals, and those of thecontrol circuit and of the buffer circuits which are in the same shiftregister unit also are coupled to different system clock signalterminals. Therefore, the clock signal terminals of every two buffercircuits in each drive group can be made to receive different clocksignals when the resolution of the picture to be displayed is equivalentto the intrinsic resolution of the display device. In particular, astart signal can be fed to the start signal terminal, and the gate scansignals sequentially output from the signal output terminals of thebuffer circuits from top to bottom may in turn constitute a certainphase difference, so that all rows of gate lines can be scannedprogressively. In this case, the display device employing the gate drivecircuit can display contents at its intrinsic resolution.

Alternatively, when the resolution of the picture to be displayed islower than the intrinsic resolution of the display device, the clocksignal terminals of at least two buffer circuits in each shift registerunit can be made to receive the same clock signals. As such, the gatescan signals output from the signal output terminals of the above atleast two buffer circuits would be synchronized so that the gate linesrespectively coupled to the two buffer circuits can be scannedsimultaneously. In this case, the display device employing the gatedrive circuit can display contents at a resolution lower than itsintrinsic resolution, thus achieving the purpose of lowering the displaypower consumption.

As would be understood by those of ordinary skill in the art, all orpart of the steps of the method embodiments described above may beaccomplished by means of hardware in combination with programinstructions which may be stored in a computer-readable storage mediumand which at execution may perform the steps of the method embodimentsas described above. The storage medium may include a variety of media,such as a ROM, RAM, disk, optical disk, or any other medium which canstore program code.

The foregoing description merely depicts some exemplary embodiments ofthe disclosure and thus is not intended as limiting the scope of thedisclosure. Any variations or substitutions that can be readily thoughtof by a person skilled in the art in light of the scope of thedisclosure shall all be covered within the protection of the disclosure.Therefore, the scope of the disclosure is defined only by the appendedclaims.

What is claimed is:
 1. A shift register unit cascaded in a gate drivecircuit, wherein the shift register unit comprises: a control circuitconfigured to output a control signal, at least two buffer circuitscoupled to the control circuit, each of the at least two buffer circuitsconfigured to output a scan signal to a gate line, wherein the controlcircuit comprises: a first pull-up control circuit coupled to a firstsignal input terminal, a signal output terminal of the control circuit,and a first voltage terminal, the first pull-up control circuitconfigured to output a signal of the first voltage terminal to thesignal output terminal of the control circuit under control of a signalof the first signal input terminal; a first pull-down control circuitcoupled to a first clock signal terminal, a second clock signalterminal, the first signal input terminal, a second voltage terminal, afourth voltage terminal, and a first pull-down node, the first pull-downcontrol circuit configured to control a voltage level of the firstpull-down node under control of signals of the first clock signalterminal, the second clock signal terminal and the first signal inputterminal; a second pull-down control circuit coupled to the first clocksignal terminal, the second clock signal terminal, the first signalinput terminal, a third voltage terminal, the fourth voltage terminal,and a second pull-down node, the second pull-down control circuitconfigured to control a voltage level of the second pull-down node undercontrol of signals of the first clock signal terminal, the second clocksignal terminal and the first signal input terminal; a first pull-downcircuit coupled to the first pull-down node, the signal output terminalof the control circuit, and the fourth voltage terminal, the firstpull-down circuit configured to pull a voltage at the signal outputterminal of the control circuit down to the voltage of the fourthvoltage terminal under control of a voltage level of the first pull-downnode; a second pull-down circuit coupled to the second pull-down node,the signal output terminal of the control circuit, and the fourthvoltage terminal, the second pull-down circuit configured to pull thevoltage of the signal output terminal of the control circuit down to thevoltage of the fourth voltage terminal under control of a voltage levelof the second pull-down node; and a reset circuit coupled to a secondsignal input terminal, the first voltage terminal, and the secondpull-down node, the reset circuit being configured to output a voltageof the first voltage terminal to the second pull-down node under controlof a signal of the second signal input terminal; wherein each of the atleast two buffer circuits comprises: a second pull-up control circuitcoupled to a pull-up control node, the second voltage terminal, thethird voltage terminal, and the signal output terminal of the controlcircuit, the second pull-up control circuit configured to turn on andoutput a signal of the signal output terminal of the control circuit tothe pull-up control node under control of a signal of the second voltageterminal and a signal of the third voltage terminal; a pull-up circuitcoupled to the pull-up control node, a third clock signal terminal, anda signal output terminal of the buffer circuit, the pull-up circuitbeing configured to output a signal of the third clock signal terminalto the signal output terminal of the buffer circuit under control of avoltage of the pull-up control node; a third pull-down circuit coupledto the first pull-down node, the fourth voltage terminal, and the signaloutput terminal of the buffer circuit, the third pull-down circuit beingconfigured to pull a voltage of the signal output terminal of the buffercircuit down to the voltage of the fourth voltage terminal under controlof a voltage level of the first pull-down node; and a fourth pull-downcircuit is coupled to the second pull-down node, the fourth voltageterminal, and the signal output terminal of the buffer circuit, thefourth pull-down circuit configured to pull the voltage of the signaloutput terminal of the buffer circuit down to the voltage of the fourthvoltage terminal under control of a voltage level of the secondpull-down node.
 2. The shift register unit according to claim 1, whereinthe first pull-up control circuit comprises: a first transistor, whereina gate of the first transistor is coupled to the first signal inputterminal, a first electrode of the first transistor is coupled to thefirst voltage terminal, and a second electrode thereof is coupled to thesignal output terminal of the control circuit.
 3. The shift registerunit according to claim 1, wherein the first pull-down control circuitcomprises: a second transistor, a third transistor, and a fourthtransistor; wherein a gate of the second transistor is coupled to thefirst clock signal terminal, a first electrode of the second transistoris coupled to the second voltage terminal, and a second electrodethereof is coupled to a first electrode of the third transistor; whereina gate of the third transistor is coupled to the second clock signalterminal, and a second electrode of the third transistor is coupled tothe first pull-down node; and wherein a gate of the fourth transistor iscoupled to the first signal input terminal, a first electrode of thefourth transistor is coupled to the fourth voltage terminal, and asecond electrode thereof is coupled to the first pull-down node.
 4. Theshift register unit according to claim 1, wherein the second pull-downcontrol circuit comprises a fifth transistor, a sixth transistor, and aseventh transistor; wherein a gate of the fifth transistor is coupled tothe first clock signal terminal, a first electrode of the fifthtransistor is coupled to the third voltage terminal, and a secondelectrode thereof is coupled to a first electrode of the sixthtransistor; wherein a gate of the sixth transistor is coupled to thesecond clock signal terminal, and a second electrode of the sixthtransistor is coupled to the second pull-down node; and wherein a gateof the seventh transistor is coupled to the first signal input terminal,a first electrode of the seventh transistor is coupled to the fourthvoltage terminal, and a second electrode thereof is coupled to thesecond pull-down node.
 5. The shift register unit according to claim 1,wherein the first pull-down circuit comprises: an eighth transistor,wherein a gate of the eighth transistor is coupled to the firstpull-down node, a first electrode of the eighth transistor is coupled tothe fourth voltage terminal, and a second electrode thereof is coupledto the signal output terminal of the control circuit.
 6. The shiftregister unit according to claim 1, wherein the second pull-down circuitcomprises: a ninth transistor, wherein a gate of the ninth transistor iscoupled to the second pull-down node, a first electrode of the ninthtransistor is coupled to the fourth voltage terminal, and a first secondelectrode thereof is coupled to the signal output terminal of thecontrol circuit.
 7. The shift register unit according to claim 1,wherein the reset circuit comprises: a tenth transistor, where a gate ofthe tenth transistor is coupled to the second signal input terminal, afirst electrode of the tenth transistor is coupled to the first voltageterminal, and a second electrode thereof is coupled to the secondpull-down node.
 8. The shift register unit according to claim 1, whereinthe second pull-up control circuit comprises an eleventh transistor anda twelfth transistor; wherein a gate of the eleventh transistor iscoupled to the third voltage terminal, a first electrode of the eleventhtransistor is coupled to the signal output terminal of the controlcircuit, and a second electrode thereof is coupled to the pull-upcontrol node; and wherein a gate of the twelfth transistor is coupled tothe second voltage terminal, a first electrode of the twelfth transistoris coupled to the signal output terminal of the control circuit, and asecond electrode thereof is coupled to the pull-up control node.
 9. Theshift register unit according to claim 1, wherein the pull-up circuitcomprises a thirteenth transistor and a storage capacitor; wherein agate of the thirteenth transistor is coupled to the pull-up controlnode, a first electrode of the thirteen transistor is coupled to thethird clock signal terminal, and a second electrode thereof is coupledto the signal output terminal of the buffer circuit; and wherein oneterminal of the storage capacitor is coupled to the gate of thethirteenth transistor, and another terminal thereof is coupled to thesecond electrode of the thirteenth transistor.
 10. The shift registerunit according to claim 1, wherein the third pull-down circuitcomprises: a fourteenth transistor, wherein a gate of the fourteenthtransistor is coupled to the first pull-down node, a first electrode ofthe fourteenth transistor is coupled to the fourth voltage terminal, anda second electrode thereof is coupled to the signal output terminal ofthe buffer circuit.
 11. The shift register unit according to claim 1,wherein the fourth pull-down circuit comprises: a fifteenth transistor,wherein a gate of the fifteenth transistor is coupled to the secondpull-down node, a first electrode of the fifteenth transistor is coupledto the fourth voltage terminal, and a second electrode thereof iscoupled to the signal output terminal of the buffer circuit.
 12. A gatedrive circuit, comprising the shift register unit according to claim 1.